Production of titanium metal



4 Sheets-Sheet 1 C. J. HOWARD ETAL PRODUCTION OF TITANIUM METAL II IFeb. 20, 1962 Filed Sept. 24, 1959 INVENTORS CARLTON J. HOWARD EDMUND W.SOBOLEWSKI BY ya ATTORNEY Feb. 20, 1962 c. J. HOWARD ETAL v 3,022,159

PRODUCTION OF TITANIUM METAL Filed Sept. 24, 1959 4 Sheets-Sheet 2lNVEN-TORS CARLTON J. HOWARD EDMUND W. SOBOLEWSK ATTORNEY 1962 c. J.HOWARD ETAL 3,022,159

PRODUCTION OF TITANIUM METAL Filed Sept. 24, 1959 4 Sheets-Sheet 3 g :i.I o if I I I I INVENTORS CARLTON J. HOWARD EDMUND W.SOBOLEWSK ATTORNEY'IIIIIIIII'I Feb- 20, 1962 I c. J. HOWARD ETAL 3,022,159

PRODUCTION OF TITANIUM METAL 4 Sheets-Sheet 4 Filed Sept. 24, 1959INVENTORS CARLTON J. HOWARD EDMUIB W. SOBOLEWSKI III/III).

l I I I I I I u I I I I I I I u I ATTORNEY 3,022,159 PRGDUCTION (BFTETANKUM METAL Carlton J. Howard, Liverpool, and Edmund W. Sobolewski,Syracuse, N.Y., assignors to Allied Chemical Corporation, New York,N.Y., a corporation of New York Filed Sept. 24, 1959, Ser. No. 842,103

4 Claims. (Cl. 75-84.5)

This invention relates to processes for making metallic titanium.

The prior art has proposed production of metallic titanium by reactionof metallic sodium and titanium tetrachloride by a two-stageoperation-involving relatively low temperature reaction of TiCl, andmetallic sodium dispersed on a carrier to form a particulate reactionproduct comprising principally NaCl and metallic titanium in unstableform, followed by a high temperature stabilization procedure carried outat temperatures above the melting point of NaCl for the purpose ofconverting the initially unstable metallic titanium to titanium spongewhich is stable in air. Processes of this type are disclosed for examplein Hansley U.S.P. 2,824,799 of February 25,1958, Quin U.S.P. 2,827,371of March 18, 1958, and 1n Follows-Keene U.S.P. 2,882,144 of April 14,1959. The Follows-Keene patent discloses a continuous method forcarrying out the low temperature reaction to form the low temperaturereaction product containing sodium chloride and unstable metallictitanium. According to prior art, the high temperature stabilization hasbeen carried out as an expensive, time consuming, batch operation.

During high temperature stabilization, the physical forms of materialpresent in the stabilizing zone include liquid NaCl, a pasty gummymixture of partly melted NaCl and solids, and solid granules oragglomerates of metallic titanium. Under most conditions, the massundergoing stabilization is highly adherent to metal surfaces. Theeconomic advantages of putting the stabilization step on a continuousbasis are self-evident. However, because of the inherent gummy andrelatively immobile characteristics of the material being stabilized,any continuous stabilizing apparatus of necessity involves use ofmechanical facilities made of metal to carry or work the materialundergoing stabilization thru the high temperature stabilization zone.However, the tenacity with which such material adheres to metal surfacesis so great that this factor of high adherence has been major cause ofnullifying prior attempts to develop satisfactory continuousstabilization.

The prior art suggests carrying out the low temperature TiCh-dispersedNa reaction in such ways that the reaction product contains total sodiumin a range vary ing'from a few percent stoichiometric deficiency (i.e.an excess of TiCl to the stoichiometric equivalent, and thruafew-percent sodium excess over stoichiometric requirements. It will beunderstood that low temperature reaction product which may be made inaccordance With prior art proposals contains Na of NaCl. In mostoperations there is some relatively small incomplete reaction, and inthis situation the reaction product contains a small amount ofsubchlorides of Ti and a correspondingly small amount of unreactedstoichiometric sodium. If the reaction product was made under conditionsin which sodium was fed in quantity in small excess of stoichiometricrequirements, the reaction product contains, in addition to Na of NaCland any unreacted stoichiometric Na, a further quantity of Na in amountcorresponding to such excess over stoichiometric. In the case of a lowtemperature process in which a stoichiometric deficiency of Na has beenemployed, total sodium of the reaction product includes only the Na ofNaCl and the Na which corresponds to whatever the small subchloridescontent may be. Hence, as used herein, the expression total sodiumincludes free and combined Na, i.e. of NaCl, any unreactedstoichiometric Na which corresponds to small subchloride content, andany Na which was charged to the low temperature reaction in excess ofstoichiometric requirements for the TiCl fed. Free sodium designates Nain excess of stoichiometric Na, and excludes stoichiometric andunreacted Na. From another viewpoint, low temperature reaction productssuggested by the prior art, with respect to total sodium,

may be said to have a negative titre i.e. deficient in stoichiometric Na(excess TiC14), ora neutral titre i.e. contains a stoichiometric amountof Na, or a positive titre i.e. contains some free Na in excess ofstoichiometric requirements. r

Investigations on which the present invention are based show' thatsuccessful continuous high temperature stabilization, looking mostlytoward controlling the degree of adherence of material undergoingstabilization to metal equipment used in a continuous furnace andforming quality product, depends largely upon factors such as thephysical form of the low temperature reaction prod. net to bestabilized, e.g. whether particulate or otherwise, the total sodiumcontent of the low temperature reaction product, and the temperatureprevailing at the point Where the stabilized material is .finallyremoved mechanically from contact with the metal apparatus elementsemployed to continuously carry or work the material to be stabilizedthru the stabilization zone.

The object of this invention is to provide a process by which theunstable metallic titanium of material consisting initially of anon-adherent particulate reaction prod! uct containing NaCl and unstableTi, and having certain compositions with regard to total sodium contentwhether negative, neutral or positive titres, and formed by drywayreaction of metallic sodium and titanium tetrachloride at reactiveelevated temperature above the melting point of sodium and substantiallybelow the, melting point of sodium chloride, may be continuouslystabilized in compacted form at temperature above the melting point ofsodium chloride.

The invention, objects and advantages thereof, may be understood fromconsideration of the following description taken in conjunction with theaccompanying drawings diagrammatically illustrating an embodiment ofapparatus in which practice of the invention process may be effected. Inthe drawings:

FIG. 1 is a vertical longitudinal section of a furnace adapted forcontinuous high temperature stabilization of the low temperaturereaction product under consideration;

FIG. 2 shows mostly in elevation a cooler-crusher into which heattreated material from the furnace of FIG. 1 may be discharged, crushedand cooled;

FIG. 3 is a vertical section taken approximately on the line 3-3 of FIG.1;

FIG. 4 is anenlarged sectional detail of apparatus for feeding materialto be treated into one end of the furnace;

FIG. 5 is an enlarged sectional detail of a seal for withdrawingby-product sodium chloride as liquid from the furnace; and

FIG. 6 is a diagrammatic longitudinal vertical section of a compactorfor pelletizing initially particulate low temperature reaction product.

Referring to FIG. 1, 10 indicates an elongated openended muffie,circular in transverse vertical section, which may be made of anysatisfactory heat and corrosion resistant material, such as Incoloyplate, of suitable thickness. The mufile is provided with end plugs 11and 12 which may consist of hollow metallic shells of Incoloy platefilled with insulating brick to the inner sides of which are attachedelectric grid-type heaters 13 and 14. The plugs are formed with flangesfor bolting to the muflle ends to make a gas-tight unit. Tubes 16 in theend plugs accomodate sight glasses. The muflle is provided on the topside with a solid material feed nozzle 18, a cleanout nozzle 19, and onthe bottom side with a liquid salt (NaCl) discharge nozzle 21, adownwardly directed liquid salt drain pipe 23 (FIG. and a heat-treatedmaterial discharge nozzle 24 (FIG. 1) the bottom of which opens into adischarge leg 25 having on the lower periphery a flange 26.

FIG. 4 illustrates in vertical section an arrangement which may beemployed in conjunction with nozzle 18 (FIG. I) for feeding pelleted lowtemperature reaction product into mufile 10. The feeder of FIG. 4 maycomprise a chute 30 including a circular flange 31 adapted to registerwith flange 33 of nozzle 18. The rear lower end 35 of the chute extendsdownwardly and terminates just clear of a belt surface in the mufile asindicated at 36, FIG. 1, while the lower forward end of the chute is cutaway as at 38, FIG. 4, to afford a relatively large opening whichprovides for mowing-up of pellets on the feed end of the belt.

FIG. 5 shows a liquid salt drain and a gas seal for the mufile. Thebottom of the muffie is formed so as to provide gentle slopes from themufile ends to muffle drain pipe 23 which projects downwardly into a cup47 tapered to a point at the bottom. Similarly tapered rod 48 dependsfrom the under end of the taper point. The upper outer end of the cup 47may be welded, as by spaced apart webs 50, to the upper end of acylindrical sleeve 51 the lower end of which terminates in a flange 53for attachment to fiange 54 on the bottom of nozzle 21. According tothis arrangement, liquid salt fills cup 47, overflows the upperperiphery thereof, and runs down thru the annulus 55 between the outersurface of the cup and the inside of the upper end of sleeve 51. Liquidsalt collecting in the cup forms a gas seal, and liquid salt in annulus55 is discharged therefrom via rod 43 and funnel 56 which cooperate tominimize contact of liquid salt with the inner faceof the lower end ofsleeve 51 which opens into a liquid salt receptacle not shown.

The heat-treated material discharge nozzle 24 (FIG. 1') may berectangular in horizontal section and tapered substantially toward thebottom end which opens into discharge leg 25 of eliptical horizontalsection. The upper edge of nozzle 24 may be welded to the edge of acorresponding opening in the muffie shell, and near the lower end nozzle24 has welded thereto the upper periphery of an inverted cone-like apron60 the lower edge of which is. welded to theupper end of the dischargeleg 25. As shown in FIG. l,the lower end of nozzle 24 projects down intothe upper end of discharge leg 25, and configuration of the adjacentparts is such as to afford a substantial annulus between the bottom ofthe discharge nozzle and the inside of the discharge leg, thisarrangement being preferred in order to prevent direct contact, with thewalls of discharge leg 25, of hot material discharged thru the nozzle24.

The muffie (FIG. 1), nozzles 18,19, 21 and 24,

and discharge leg 25 are enclosed in an electric furnace assemblycomprising an outer steel shell 63, and insulating firebrick 64 theinner surfaces of which are sufiiciently tend over the entire width ofthe belt.

provided with a bevel knife edge,

spaced from the exteriors of the mutfle, the salt drain, dischargenozzle 24 and the discharge leg 25 to accommodate electric grid-typeheaters 66. These heaters, and also heaters 13 and 14 in the end plugs,are arranged in suitable unit relation so that variable amounts anddegrees of heat, as desired, may be applied to different parts of theapparatus.

Mufile 10 is provided with an axially disposed endless conveyorextending from beneath feed nozzle 18 to solid material discharge nozzle24. Since the mechanical structural details of the conveyor constituteno part of this invention, for brevity, conveyor constructionillustrated in the drawings is highly diagrammatic. As indicated in FIG.3, longitudinally disposed angle irons or rails 70 are Welded at theiredges to the lower inner circumference of the mufile and afford supportfor the conveyor and associated elements. In FIG. 3, 71 denotesgenerally a longitudinal framework which extends axially of the muffleand to which in one way or another all elements of the conveyor assemblyare fixedly or movably attached. Lower and upper tracks 73 and 74support and guide the edges of an endless conveyor belt 75 equipped atthe longitudinal outer edges with selvage plates 77, fabricated as knownin the conveyor art and functioning to prevent spilling of solidmaterial over the edges of the upper run of the belt.

Suitably journalled in association with the conveyor frame 71 are shafts78 and 79 (FIG. 1) carrying belt drive drums. One end of each driveshaft projects outwardly thru the furnace shell and thru gas-tightglands to facilitate connection to the source of power for rotating theshafts and the associated belt drive drums. 'Mufile 10 is anchored atthe material feed end, and the entire conveyor unit is preferablyanchored at the solids discharge end of the muflle while the feed end ofthe conveyor assembly is free to move axially to provide for varyingthermal conditions of expansion and contraction. Further, feed end shaft78 is mounted so as to permit axial movement with regard to the conveyorframe, the bearings of shaft 78 being yoked to the inner end of a rod 81(FIG. 1) which is axially movable in gas-tight gland 82. The outer endof rod 81 may be connected to any suitable mechanism, not shown, bywhich tension of the endless belt may be observed and adjusted.Preferably both shafts 78 and 79 are driven members so that the belt isdriven from both ends.

The belt drive drums may be cast out of type ACI-HT stainless steel andprovided with lug teeth spanning the width of the drums. The beltpreferably employed is of the plate type, as distinguished from meshtype, known in the art and illustrated for example in U.S.P. 2,779,579of January 29, 1957. Preferably, construction of the plate belt is suchthat the inner and outer surfaces of the plates are concaved andconvexed respectively in accordance with the curvature of the drivedrums. The belt plates, belt pins and selvage plates may be made ofACI-H'I' stainless steel (Ni 35--Cr 15). Plate type belts are more orless perforate at the plate and pin linkages, and permit drainage ofliquid NaCl thru both upper and lower belt runs.

A scraperblade 85 (FIG. 1) which may be made of e.g. No. 330 stainlesssteel plate, is attached rigidly to the end of the conveyor frarneinposition as to ex- The blade is and is attached to the frame so that theknife edge is preferably tangential of the belt at a point slightlyabove the horizontal center line of the drum.

Heat treated material, i.e. spalt, is discharged from the conveyor beltthru discharge nozzle 24 and discharge leg 25 of FIG. 1 into acooler-crusher shown diagrammatically in FIG. 2. The cooler-crusherassembly comprises a cylindrical steel shell housing a rotating shaft 91mounted in gas tight bearings and carrying steel spud paddles 93.Stationary stud paddles 94 are welded at their lower ends to the coolershell to facilitate crushing. An inlet nozzle 96 of ellipticalhorizontal section provided with a flange 97 for connection to flange26, affords communication between the bottom of furnace discharge leg'25 and the interior of crusher-cooler 90. Disintegrated solidsdischarged from the crusher-cooler drop thru an outlet nozzle 99 into agas-lock chamber 100 outlet ofwhich communicates with a spalt coolingbin 102 which is one of a plurality of parallelly arranged similar bins.The entire cooler-crusher assembly may rest on spring supports 1% topermit vertical expansion, and on roller bearings indicated at 105 toallow for horizontal movement.

FIG. 6 represents diagrammatically a compactor which may be employed tocompress non-adherent particulate unstable low-temperature reactionproduct into pellets. The pelletizer comprises a feed nozzle 111 apiston 111 and a piston 112, a pellet forming chamber 114, and adischarge nozzle 115, the pistons being operated by hydraulic cylinders116 and 117. Inlet nozzle 110 is connected to the outlet end of a screwconveyor, not shown, which transfers particulate low-temperaturereaction product from a storage bin to compactor inlet 110. Knownelectrical cam-timer arrangements may be used to sequence the movementsof the cylinders to facilitate formation of pellets of desired densityand size, and also at a desired rate. For example, piston sequence maybe as follows: particulate low temperature reaction product falls frominlet 110 into chamber 114, while piston 111 moves out of the chamberand piston 112 moves into the chamber sufficiently to close off outlet115; piston 111 moves forward in chamber 114 a distance sufiicient toeffect pelletizing; piston 112 withdraws to the position shown in FIG.6; piston 111 completes the forward stroke sufliciently to drop thepellet into outlet 115. The flange 118 of the pelletizer outlet isconnected to flange 31 of the chute 31? as indicated in FIG. 4.

It will be understood that the interior of the apparatus described isgas-tight, and that in operation the interior of the entire apparatus,from the interior of the storage bin for the unstable low temperaturereaction product up to and including cooling bin 102, is maintainedunder a relatively low positive pressure of an inert gas e.g. argon,accessories such as piping, valves, inlets, etc. for maintaining aninert atmosphere within the apparatus not being shown. Selection ofconstruction materials not mentioned herein are within the skill of theart.

' One control factor of major importance in successful continuousstabilization of particulate loW temperature reaction product is thecomposition of the latter with regard to the presence or absence of freeNa. For con venience, this control factor is referred to herein astitre, and what is meant by negative, neutral-and positive titres is aspreviously explained. Titre of any given sample may be determined by anysuitable analysis method which takes into account all sodium presentexcept the reacted sodium which has gone over to NaCl in the lowtemperature reaction. To illustrate, and assuming a sample having apositive titre (i.e. contains Na above stoichiometric requirements), thesample may be treated with water and e.g. hydrochloric acid in excess. naddition of Water, the unreacted Na goes to NaOH and the correspondingamounts of titanium chlorides hydrolyze to TiO and HCl, the HCl tying upwith the NaOH to form NaCl. Thuswise, in the case of a sample containingan excess of Na over stoichiometric, the unreacted Na is eliminated fromfurther consideration. Withregard to the Na present over and abovestoichiometric, such Na with water goes to NaOH, and the latter reactingwith a known amount of HQ! in excess goes to NaCl plus the HCl excess.Back titration with NaOH to neutralize the excess HCl gives the amountof HCl used to tie up with the Na present over and above stoichiometricrequirements, this amount of Na being then determinable on a weightbasis, The relation between this thus determined weight and thetheoretical stoichiometric amount of Na in the given sample provides apercentage value denoting the excess of sodium over stoichiometric andindicated herein as positive percent titre, e.g. a positive 1% titreindicates that the sample as to Na contains an excess of 1% by weight ofstoichiometric Na requirements. Similarly, assuming a low temperaturereaction product deficient in stoichiometric Na, on treatment of thesample with water and hydrochloric acid, the unreacted Na and thecorresponding amounts of titanium chlorides go to NaCl as before.However, because of stoichiometric Na deficiency there is formed acorresponding amount of HCl which amount is the difference between totalHCl present and the HCl added to the sample with the Water. The amountof Na reactable with the thus formed HCl to produce NaCl is the weightmeasure of the stoichiometric deficiency of Na, and the weight relationof such amount of Na to the theoretical stoichiometric amount of Na inthe sample gives a negative percent titre, e.g. a negative 1% titreindicates that the sample as to Na is short 1% by weight ofstoichiometric Na requirements.

According to the invention, it has been found that low temperaturereaction product initially inparticulate' form-whether of negative,neutral or positive titremay be continuously stabilized, by passing thesame on. a suitable metal supporting surface moving thru a sta-,bilization zone maintained at stabilizing temperature and for anadequate retention time, and may be satisfactorily disengaged from ametal supporting surface provided that the initially particulate lowtemperature reaction product is pelleted at certain minimum pressure,and provided that the temperature in the zone of disengagement of thestabilized material from the moving surface, on termination of retentiontime, is maintained below the melting point of sodium chloride. Briefly,practive of the invention comprises continuously pelletiz ing theinitially particulate reaction product'at pressure not less than 3600lbs/sq. in., continuously feeding the pelleted material into one end ofa high temperature stabilizing zone and onto a supporting surfacecontinu: ously moving thru such zone, continuously moving the surfaceand the pelleted material thereon thru the Zone while subjecting suchmaterial to stabilizing temperature substantially above the meltingpoint of sodium chloride, regulating rate of movement of the surface andof the material thru the zone so as to provide a retention time for thematerial such that, on discharge from the zone of the material andcooling thereof to relatively low temperature, the metallic titaniumcontent of said cooled material is stable in air, continuouslydisengaging the heat-treated solid material from the surface ontermination of said retention time while main taining temperature belowthe melting point of sodium chloride in the zone of said disengagement,and continuously withdrawing disengaged solid material from said zone,the entire foregoing operation being carried out in an inert atmosphere.I

With regard to the low temperature reaction product utilized, theinvention process is directed to stabilizing the unstable metallictitanium of material consisting of an initially non-adherent particulatereaction product containing NaCl and unstable Ti and formed by drywayreaction of metallic sodium andtitanium tetrachloride at reactiveelevated temperature above the melting point of sodium and substantiallybelow the melting point of sodium chloride. While thereactiontemperatures employed in the manufacture of the low temperaturereaction product may range from above the melting point of sodium to atemperature reasonably below the melting point of sodium chloride, suchtemperatures are more practicably in the approximate range of 650 C., itbeing preferred, in practice of the instant invention, to utilize'l'owtemperature reaction product which 7 has been made in the temperaturerange of 175 C. up to say 300-400 C.

As above indicated, prior art suggests manufacture of low temperaturereaction product in such ways that the various particulate products mayhave negative, substantially neutral, or positive titres. The presentinvention affords the highly important advantage that the particulateproducts of the art may be continuously stabilized whether such productswith respect to total sodium have negative, neutral or positive titres.It has been found that in order to continuously stabilize lowtemperature reaction product initially in the non-adherent particulateform and having total sodium ranging from negative titre thru positivetitre, one factor upon which successful operation depends is that suchproduct should be pelleted at pressure not less than about 3600 lbs/sq.in.

Titres of low temperature reaction products in particulate form made bymethods of the prior art may vary over a relatively broad range and mayhave a negative titre down to say 3% or more, up thru neutral, and to apositive titre up to 3% or more. On the positive side, the particulateproducts employed in practice of this invention may have a titre up toabout 2%, desirably not more than about 1.75%. Positive titres amountingto more than about 2% are undesirable since investigations indicate thatgreater excess sodium values atiord no significantly increaseddisengagement properties, and in some instances appear to deleteriouslyaffect Brinnell hardness number of the ultimate metallic titaniumproduct. Investigations show that, particularly with regard toenhancement of spalt disengagement properties of pelleted materiahlowBrinnell number, ultimate product quality, and low fines contentofground spalt, use of particulate reaction products having titres in therange of just above neutral i;e. about plus 0.2% down to a moderatenegative value afiord significant advantages. Maximum negative titrevalue, while not appearing to be as notably important as maximum titrevalue on the positive side, is desirably not higher than about 2.5%. Inthe better embodiments of the invention in' which the material issubjected to stabilization in pelleted form, it is preferred to utilize,for pelleting, particulate low temperature reduction products which havetitres substantially in the range of negative 1.0% up to positive 0.2%,overall best quality ultimate product being obtained when titres aresubstantially in the range of negative 0.2% to positive 0.2%.

In practice, the particulate material to be stabilized preferably iscontinuously pelleted as in a compactor such as that of FIG. 6 underpressure conditions not less than 3600 lbs/sq. in., and preferably ofthe order of 3800-4200 lbs/sq. in. It has been found that pelletizingpressures, and initial pellet size to a significant extent, contributecritically to the disengagement properties of the spalt on terminationof stabilizing furnace retention time. For best structural stability,preferably the pellets employed are made in cylindrical form at thepressures noted and so as to have a diameter/length ratio not greaterthan about 1.4. In practice, pellets about 1.4 inches in diameter andone inch or less in length have been employed successfully,

The pelleted material is continuously fed into a stabilizing zone of thetype described, eg via a feed device such as exemplified in FIG. 4.

Stabilization temperature is above the melting point (804 C.) of sodiumchloride, a practicable working low temperature limit being about 850 C.Stabilization temperature may vary within the range of about 850-l0000., although average temperatures of around 900 C. are preferred, andtemperatures above about 950 C. are undesirable because of increasedtendency for spalt to adhere to and incipiently alloy with metal of theconveying surface.

Pelletized material fed into the stabilizer thru chute 30 drops onto thereceiving end of the moving supporting surface e.g. the belt, andlargely because of the form of opening in the lower end of the chute,spreads out in relatively layer form mowing up at the center of the beltand tapering oil at the edges. In usual practice, pellets on the beltmaymow up to about 6 in. deep at the center and taper oii to a singlepellet depth toward the edges.

Retention time of material being stabilized in the stabilizing zone isvariable as is appreciated by the skill of the art. In any event,retention time is such that the metallic Ti content of the spaltproduced in and discharged from the stabilizing zone, when cooled torelatively low temperatures, is stable in air. With this objective inview, depending upon the capacity of the particular apparatus at hand,desirable stabilizing temperature and other operating factors apparentto the skill of the art, rate of movement of pelleted material thru thestabilizing zone and retention time therein may be established by testrun for any given set of conditions. In procedures such as exemplifiedherein, retention time preferably should be not less than 3 hours.Temperature to which the spalt should be'cooled before exposure to air,e.g. spalt collecting in the spalt cooling bin 102 of FIG. 2, may lie inthe range of from say 40-80 (3-, and is preferably not more than 100 C.

A marked advantage resulting from herein continuous stabilization isthat lay-product NaCl may be continuously drained from solids orsemi-solids all during the passage of the same thru the stabilizationzone. Notwithstanding the relatively high pressure of pelleting and theresulting density of pellets, a major portion of the by-product NaCldrains out of the pellets. In practice as illustrated, about 75 to ofthe total salt content of the material fed may be drained away andseparately removed from the system. There is no relative movement asbetween the more or less perforate carrying belt and the materialthereon while the two are moving thru the. stabilizing zone.

ln'addition to the previously described total sodium content factor ofthe material ted to the stabilizing zone, it has been found that, withrespect to providing satisfactory conditions 'for disengagement of spaltfrom its supportlng surface at the end of retention time, anotherequally important and controlling factor lies in the temperatureexisting in the zone of disengagement of the spalt from the moving metalsupporting surface. In this connection, when stabilizing the materialdescribed in pellet form, it has been found that the zone at and m theimmediate vicinity of spalt disengagement should be maintained at atemperature substantially below the melt ng point of NaCl. Thistemperature, a practicable maximum, should be a workable number ofdegrees C. below the melting point of NaCl, and ordinarily should not bemore than about 775 C., and a good operating maximum temperature isabout 750 C. Depending upon the operating facilities at hand, the lowerthis temperature the better since friability of the cluster-like spaltincreases at lower temperatures and greatly improves spalt disengagementand crushing. Comparable temperatures are desirably maintained While thespalt is being transferred, e.g. thru the discharge nozzle 24 anddischarge leg 25 of FIG. 1 into a crusher-cooler such as illustrated inFIG. 2.

The following Example 1 illustrates practice of the invention. Theapparatus employed was substantially the same as described. In themufile, a plate-type continuous belt about 15 inches wide was used. Thelength of the belt, strung over 10 in. OD. drive drums, was such thatthe drum drive shafts were about 9 ft. apart (cold furnace). Data givenare based on averages of a 23-day continuous run.

The low temperature Na-TiCl reaction product subjected to stabilizationwas made in a conjunctive continuous run in accordancewith the processdescribed in the above-mentioned Follows-Keene patent. In the lowtemperature reaction vaporous TiCl and sodium dispersed on reactionproduct of a previous cycle were reacted at temperatures in the range ofabout 230-260 C. This reaction product consisted of 12-14% unstablemetallic Ti, the balance including relatively small amount ofsubchlorides of titanium and a corresponding small amount of unreactedsodium, average titre was in the range of about negative 0.55% topositive 0.01%, the remainder being sodium chloride. A typical screenanalysis of material of this nature is as follows:

The low temperature product was made and maintained under an argonblanket.

The free-flowing, particulate low temperature reaction product wastransferred under argon blanket from a storage bin by a screw conveyor,held at internal temperature of about 125 C., to the feed inlet of ahydraulic compactor unit such as illustrated in FIG. 6. This compactorwas operated by sequencemechanism known in the art to punch out pelletsabout 1.4 in. in diameter and about %-2 in. long under pressure of 4000lbs./in. at rate of 4-6 pellets per minute. These pellets were droppedinto the feed mechanism of the furnace via a chute such as 30 of FIG. 4.Rate of feed of pelletizcd reaction product to the stabilizing furnacewas such that 30-40 lbs./hr. of incoming material was dropped onto thereceiving end of the belt conveyor. Electrically generated heat wasapplied to the mufiie in quantity such that temperature in approximatelythe front 8 feet of the belt was maintained at about 900 C. while thetemperature in approximately the rear one foot of the belt and in thezone of disengagement of spalt at the discharge end of the belt wasmaintained below about 740 C. No heat was applied to the spalt dischargenozzle 24 or to the furnace discharge leg 25. The material on the beltwas forwarded thru the stabilizing zone at a rate of about 2.0 to 2.25ft./hr., thus providingan overall retention 'time of titanium materialon the belt of about 44.5

hours.

During this period 20-25 lbs./hr. of liquid NaCl drained away from thematerial on the belt, flowed into the salt sealin the bottom of themufile and was discharged from the apparatus. Hence, about 75 to 85weight percent of the total NaCl present in the stabilizing zone drainedaway from the material on the belt and was removed from the system asliquid NaCl. While most of the pellets sinter together superficially atpoints and lines of contact, in general the pellets retained their shapeand shrank to about one-fifth original size. The spalt in chunks,appearing mostly in the form of semi-fused together clusters of grapes,was satisfactorily stripped from the end of the belt by means of ascraper blade positioned, with respect to the belt, substantially aspreviously described. Stripped spalt dropped thru the discharge nozzle24 and the discharge leg 25 into the cooler-crusher. Rate of dischargeof spalt off the belt was about 15 lbs./hr., and the spalt contained inthe range of 45-60% metallic titanium. In the coller-crusher, the paddleshaft was driven at a rate of about 100 rpm, and the spalt was broken upinto chunks of about one inch maximum dimension, i.e. small enough to behandleable in the succeeding operation. The broken spalt product of thecooler-crusher was conveyed to and dropped into one of a' plurality ofparallelly arranged-cooling chambers which when filled was isolated inthe cooler-crusher atmosphere.

In the cooling chamber, the material was allowed to cool to about 40 C.Up to this point, the entire stabilizing operation was carried out undera positive pressure of argon of about 3-4 in. of water.

On completion of cooling, the argon blanket was re leased and themetallic titanium of the spalt was stable in air. The spalt was thencrushed to maximum size of about in. The splat was salt leached bywashing 3 times in water containing about 1% of Hcl, the quantity ofacidified water used in each wash being roughly 1.25 times the Weight ofsolids. The residual, stable metallic titanium sponge was vacuum driedat temperature not in excess of about 100 C. After arc melting, as knownin the art, the metallic titanium product had averageBrinnell hardnessnumber of 125. In the course of the run about 11,800 lbs. of particulatelow temperature reaction product of the bulk density of about 7075lbs/ft. were fed to the process; about 7700 lbs. of NaCl were drainedout as liquid thru the salt seal; about 4100 lbs. of spalt ously fed tothe (crushed bulk density about 103 lbs./ft. were discharged from thebelt; and sponge titanium recovery was about 1900 lbs., i.e. about 94%of theory. Bulk density of the sponge was about 66 lbs./ft.

In the following examples, apparatus employed was the same as in Example1, and operating conditions, except as indicated, were substantially thesame as described in Example 1. 7

Example 2.The operation was an 11-day continuous, run. Average titre ofthe particulate low temperature NaTiCl reaction product employed wasplus 0.005%, i.e. substantially neutral titre. About 5600 lbs. of theparticulate product were continuously fed to the pelletizer, and theresulting pellets were continuously charged into the stabilizingfurnace. During the course of the run, about 4200 lbs. of NaCl weredrained away from the material on the moving belt and withdrawn from thefurnace thru the liquid salt outlet. Spalt produced and discharged fromthe furnace amounted to about 1400 lbs. and the spalt contained about800 lbs. of sponge titanium. The spalt was handled as in Example 1, andafter arc melting, the metallic titanium product had an average Brinnellhardness number of 125.

Example 3.The operation was a 2-day continuous run. Average titre of theparticulate low temperature NaTiCl reaction product employed was plus0.28%. About 970 lbs. of the particulate product were continupelletizer,and the resulting pellets were continuously charged into the stabilizingfurnace. During the course of the run, about 720 lbs. of NaCl weredrained away from the material on the moving belt and withdrawn from thefurnace thru the liquid salt outlet. Spalt produced and discharged fromthe furnace amounted to about 250 lbs., and the spalt contained aboutlbs. of sponge titanium. The spalt was handled as in Example 1, andafter arc melting, the metallic titanium product had an average Brinnellhardness number of 127.

We claim: i

1. The process for continuously stabilizing the unstable metallic Ti ofmaterial consisting of a nonadherent particulate reaction productcontaining NaCl and unstable Ti and formed by dry-way reaction ofmetallic Na and TiCL, at reactive elevated temperature above the meltingpoint of Na and below the melting point of NaCl, which process comprisescontinuously at pressure not less than 3600 lbs/sq. in. pelletizing saidmaterial having a titre substantially in the range of negative 2.5% topositive 0.28%, continuously feeding said pelletized material into oneend of a high temperature stabilizing zone and onto a supporting surfacecontinuously moving thru said zone, continuously moving said surface andthe pelletized material thereon thru said zone while subjecting saidmaterial to stabilizing temperature above the melting point of NaCl,regulating rate of movement of said surface and of said material thrusaid zone so as to provide a retention time for said material such that,on discharge from said zone of said material and cooling thereof totemperature not substantially higher than 100 C., the metallic Ticontent of said cooled material is stable in air, continuously drainingliquid sodium chloride away from said material during passage thereofthru said zone and continuously separately discharging such liquid fromsaid zone, on termination of said retention time continuouslymechanically disengaging such heat-treated solid material from saidsurface while maintaining temperature below about 750 C. in the zone ofsaid disengagement, the entire foregoing operation being carried out inan inert atmosphere, and continuously recovering stabilized metallic Ti.

2. The process of claim 1 in which the material pelletized has a titresubstantially in the range of negative 0.2% to positive 028% 3. Theprocess of claim 1 in which the material pelletized has a titresubstantially in the range of negative 1.0% to positive 0.28%

4. The process for continuously stabilizing the unstable metallic Ti ofmaterial consisting of a non-adherent particulate reaction productcontaining NaCl and unstable Ti and formed by dry-way reaction ofmetallic Na and TiCL, at reactive elevated temperature above the meltingpoint of Na and below the melting point of NaCl, which process comprisescontinuously at pressure of the order of 3800 4200 lbs./ sq. in.pelletizing said material having a titre substantially in the range ofnegative 1.0% to positive 0.28%, continuously feeding said pelletedmaterial into one end of a high temperature stabilizing zone and onto asupporting surface continuously moving thru said zone,

continuously moving said surface and the pelleted ma-v terial thereonthru said zone while subjecting said material to stabilizing temperaturesubstantially in the range of 850-900 C., regulating rate of movement ofsaid surface and of said material thru said zone so as to provide aretention time for said material not less than about 3 hours but suchthat, on discharge from said zone of said material and cooling thereofto temperature not substantially higher than C., the metallic Ti contentof said cooled material is stable in air, continuously draining liquidsodium chloride away from said material during passage thereof thru saidzone and continuously separately discharging such liquid from said zone,on termination of saidretention time continuously mechanicallydisengaging said heat-treated solid material from said surface Whilemaintaining temperature below about 750 C. in the zone of saiddisengagement, the entire foregoing operation being carried out in aninert atmosphere, and continuously recovering stabilized metallictitanium.

References Cited in the file of this patent UNITED STATES PATENTS2,564,337 Maddex Aug. 14, 1951 2,734,244 Herres Feb. 14, 1956 2,827,371Quin Mar. 18, 1958 2,861,791 Chisholm et al Nov. 25, 1958 2,882,144Follows et a1 Apr. 14, 1959 2,895,823 Lynskey July 21, 1959 2,944,888Quin July 12, 1960 FOREIGN PATENTS 720,517 Great Britain Dec. 22, 1954

1. THE PROCESS FOR CONTINOUSLY STABILIZING THE UNSTABLE METALLIC TI OFMATERIAL CONSISTING OF A NONADHERENT PARTICULATE REACTION PRODUCTCONTAINING NACL AND UNSTABLE TI AND FORMED BY DRY-WAY REACTION OFMETALLIC NA AND TICL4 AT REACTIVE ELEVATED TEMPERTURE ABOVE THE MELTINGPOINT OF NA AND BELOW THE MELTING POINT OF NACL, WHICH PROCESS COMPRISESCONTINOUSLY AT PRESSURE NOT LESS THAN 3600 LBS./SQ. IN. PELLETIZING SAIDMATERIAL HAVING A TITRE SUBSTANTIALLY IN THE RANGE OF NEGATIVE 2.5% TOPOSITIVE 0.28%, CONTINUOUSLY FEEDING SAID PELLETIZED MATERIAL INTO ONEEND OF A HIGH TEMPERATURE STABILIZING ZONE AND ONTO A SUPPORTING SURFACECONTINUOUSLY MOVING THRU SAID ZONE, CONTINUOUSLY MOVING SAID SUSRFACEAND THE PELLETIZED MATERIAL THEREON THURU SAID ZONE WHILE SUBJECTINGSAID MATERIAL TO STABILIZING TEMPERATURE ABOVE THE MELTING POINT OFNACL, REGULATING RATE OF MOVEMENT OF SAID SURFACE AND OF SAID MATERIALTHRU SAID ZONE SO AS TO PROVIDE A RETENTION TIME FOR SAID MATERIAL SUCHTHAT, ON DISCHARGE FROM SAID ZONE OF SAID MATERIAL AND COOLING THEREOFTO TEMPERATURE NOT SUBSTANTIALLY HIGHER THAN 100*C., THE METALLIC TICONTENT OF SAID COOLED MATERIAL IS STABLE IN